This invention relates to an aluminum electrolytic cell array and a method of supplying electric power to the same, and more particularly an improved aluminum electrolytic cell array and a method of supplying electric power to the same in which creation of magnetic field which causes bending and fluctuation of the surface of molten aluminum in the cell can be decreased.
As is well known in the art, aluminum is manufactured by electrolyzing in electrolytic cells alumina dissolved in an electrolytic bath consisting essentially of cryolite. The aluminum thus formed is collected in the bottom of the cell and the surface of the molten aluminum acts as an actual cathode electrode. When subjected to an external force the surface of the molten aluminum tends to bend or fluctuate causing local decrease in the interelectrode spacing as well as decrease in the current efficiency. This phenomenon becomes remarkable with the increase in the current capacity which makes it difficult to increase the capacity of the cell.
The force acting upon the molten aluminum in the electrolytic cell is mainly created by the interaction between the current flowing through the molten aluminum and magnetic field created by current flowing through bus bars extending about the cell. We have found that the force that bends or fluctuates the surface of the molten aluminum increases with the variation in the horizontal direction of the vertical component of the magnetic field in the molten aluminum, that is the gradient or slope of the vertical component of the magnetic field. In a prior art electrolytic cell installation in which a number of cells are disposed side by side, since the bus bars are disposed in a manner as will be described later the current concentrates near the shorter side wall of the cell to increase the slope of the vertical component of the magnetic field at this portion. Consequently, it has been inevitable that excessive bending or fluctuation of the surface of the molten aluminum is caused. We have now succeeded to obviate these difficulties by improving the arrangement of the bus bars about the electrolytic cell.